Nest: Get message subject in microservice controller

Created on 25 Jun 2019 · 4Comments · Source: nestjs/nest

Feature Request

Is your feature request related to a problem? Please describe.

I have an issue when I create a Nest microservices controller where I cannot retrieve the Subject of the sent message. For example, I am setting up a NATS service with a wildcard subscription for the pattern time.us.*. Here's an example of handling the subject from the docs:

await nc.subscribe('time.us.*', (err, msg) => {
    let time = "";
    switch (msg.subject) {
        case 'time.us.east':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/New_York"});
            break;
        case 'time.us.central':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Chicago"});
            break;
        case 'time.us.mountain':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Denver"});
            break;
        case 'time.us.west':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Los_Angeles"});
            break;
        default:
            time = "I don't know what you are talking about Willis";
    }
    console.log(msg.subject, time);
});

In my Nest NATS controller, I can set up the following controller function:

@Controller()
export class AppController {
  constructor(
    private readonly appService: AppService,
  ) {}

  @MessagePattern('time.us.*'')
  getTime(data: any, blah: any) {
    // can get only data from the message, not subject
    return `the time is ${Date.now()}`
  }
}

Describe the solution you'd like

I would like a way to access the subject of the received message, possibly through a second parameter in the @MessagePattern decorated function,

Teachability, Documentation, Adoption, Migration Strategy

What is the motivation / use case for changing the behavior?

Wildcard subscriptions are an important part of NATS (and probably other transports, but I am not familiar with others). Without this feature, the Nest implementation is essentially a non-starter.

microservices type

Source